1. Field of the Invention
The present invention relates to an image processing apparatus for performing predetermined processing on a read image acquired by a reading device reading an original, and an image processing method.
2. Description of the Related Art
An image reading device (scanner) for optically reading a written original and a photo and converting a read image into electronic data is widely used. A number of such image reading devices are provided not only as a single device, but also as a multifunction peripheral, such as a copying machine integrated with a printing device and a facsimile integrated with a transmission/reception function. Further, in recent years, various image processing methods have been proposed for electronic data that is read, such as the OCR (Optical Character Recognition) technique and the technique of PDF file conversion. At this time, it is regarded as important to accurately grasp, in particular, the directional properties of a read original.
For example, Japanese Patent Laid-Open No. 2001-256491 discloses the technique to read an original together with a background whose color data is known in advance and to acquire an inclination of the read original as well as separating the background and the region of the original and to correct the inclination.
By using the technique such as this described in Japanese Patent Laid-Open No. 2001-256491, even in the case where an original is oriented with an inclination, it is possible to perform OCR processing or carry out conversion into a PDF file after correcting the orientation of the original represented by electronic data, and therefore, it is made possible to efficiently acquire character information.
However, in recent image reading devices, it is common to utilize a white sheet having a high degree of whiteness as a background of an original. The reason is that ink or toner is prevented from being consumed wastefully for the region to be read other than the original at the time of printing the image after that. On the other hand, sheets used as an original include recycled paper recycled from waste paper and the degree of whiteness of the recycle paper increases year after year and has become substantially the same as that of the high-quality paper. Then, in the state where an original whose degree of whiteness is high is read together with a white sheet whose degree of whiteness is also high as a background as described above, it becomes difficult to separate the original and the background based on the difference in color data and to extract the edge of the original as described in Japanese Patent Laid-Open No. 2001-256491.